The Audeze LCD-MX4 is 20Ω at 105.0 dB/mW; the Audeze LCD-X 2021 is 20Ω at 103.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The LCD-X 2021 needs 2.0 dB more than the LCD-MX4 to reach the same loudness — 0.50 mW against 0.32 mW.
| Specification | LCD-MX4 | LCD-X 2021 |
|---|---|---|
| Impedance | 20 Ω | 20 Ω |
| Sensitivity | 105.0 dB/mW | 103.0 dB/mW |
| Sensitivity (voltage) | 122.0 dB/V | 120.0 dB/V |
| Power for 100 dB | 0.32 mW | 0.50 mW |
| Voltage for 100 dB | 80 mV | 0.10 V |
| Current for 100 dB | 4.0 mA | 5.0 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 2.50 Ω | 2.50 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
Every source in the database that drives one of them drives the other. On power, the choice between these two changes nothing about what amplifier you need.
2 sources stay below the audible-hiss threshold with the LCD-X 2021 but cross it with the LCD-MX4 (FiiO BTR11, Rupert Neve RNHP).
280 of the 280 sources here reach 100 dB on both.
The LCD-X 2021 is more demanding than 32% of the 567 non-electrostatic models in this database; the LCD-MX4 than 25%.
| dB SPL | LCD-MX4 power | LCD-MX4 voltage | LCD-X 2021 power | LCD-X 2021 voltage |
|---|---|---|---|---|
| 80 | 3.2 µW | 8 mV | 5.0 µW | 10 mV |
| 85 | 0.01 mW | 14 mV | 0.02 mW | 18 mV |
| 90 | 0.03 mW | 25 mV | 0.05 mW | 32 mV |
| 95 | 0.10 mW | 45 mV | 0.16 mW | 56 mV |
| 100 | 0.32 mW | 80 mV | 0.50 mW | 0.10 V |
| 105 | 1.0 mW | 0.14 V | 1.6 mW | 0.18 V |
| Source | Price | Headroom, LCD-MX4 | Headroom, LCD-X 2021 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 17.7 dB | 15.7 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 28.5 dB | 26.5 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 25.4 dB | 23.4 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. 67 of them also publish an output impedance low enough for both under the one-eighth rule and a noise figure that stays below the audible-hiss threshold with both.
The cheapest of the 67 is the JadeAudio JA11, at $20. It leaves 17.7 dB of headroom on the LCD-MX4 and 15.7 dB on the LCD-X 2021, its output impedance is 0.5 Ω against a one-eighth limit of 2.50 Ω for both, and its noise figure puts the hiss floor 13 dB and 15 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| LCD-MX4 | 10Hz - 50kHz | not printed | not printed |
| LCD-X 2021 | 10Hz - 50kHz | not printed | not printed |
Audeze prints the same thing for both the LCD-MX4 and the LCD-X 2021: 10Hz - 50kHz.
Neither range has a tolerance printed beside it, so the matching numbers say little.
Not a measurement; maker by maker.
Both have a page of their own. In full: Audeze LCD-MX4 and Audeze LCD-X 2021. Every figure on this page comes from what Audeze published, or is derived from it — what that maker publishes, counted.